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<nicksydney>
have a linux kernel question...
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<nicksydney>
i've read about HW breakpoint and still not sure i understand completely about this...is HW breakpoint available for most ARM architecture ?
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<nicksydney>
so the photo paper does work for pcb etching but the way to do it is to spray the pcb with water and iron continously https://www.youtube.com/watch?v=N3DGbwVXyN8
<wpwrak>
sounds complicated :)
<nicksydney>
that's what experiment all about :) complication :)
<nicksydney>
if i do fine traces i will use blue paper and if the traces are bit wider than 0.25mm than will use yellow paper :)
<DocScrutinizer05>
((is HW breakpoint available for most ARM architecture ?)) basically yes
<DocScrutinizer05>
it depends on type of ARM core, but afaik cortex have several hw breakpoints
<DocScrutinizer05>
it's basically pretty simple: a comparator on address bus of RAM
<nicksydney>
DocScrutinizer05: so if the IC support hw breakpoints that means we could single-step code like how normal debugging process works ?
<DocScrutinizer05>
yes
<DocScrutinizer05>
among other nice things. You also can trap any read/write access to a specific RAM location (think variables access)
<DocScrutinizer05>
even ranges of adresses
<nicksydney>
so for IC that have Linux support in it to use HW breakpoint we need to enable it correct ?
<nicksydney>
i meant enable in the Linux config
<DocScrutinizer05>
Linux support?
<DocScrutinizer05>
hw breakpoints are independant of tghe software that runs on the CPU
<nicksydney>
ohhh ok....so to enable it don't we have to do something first ?
<DocScrutinizer05>
usually I used them via JTAG and Lauterbch
<DocScrutinizer05>
Lauterbach even
<nicksydney>
ahhhh ok
<nicksydney>
so you mean that with JTAG (if the pin is exposed on the board) we could use HW breakpoint
<DocScrutinizer05>
you also can enable them "on board" or maybe I should call that "endocrine"
<DocScrutinizer05>
yes
<DocScrutinizer05>
you also can use Embedded Trace Macrocell
<DocScrutinizer05>
(but even that also is usable "endocrine", from within the traced OS)
<nicksydney>
i have got a board that have pin that says JTAG1 and it has 20pins does that sound correct ?
<DocScrutinizer05>
ETM does log the last maybe 2k of program code (actually it only traces branches, since everything else is static. It also can trace data)
<DocScrutinizer05>
it all depends on the software in the end of the day
<DocScrutinizer05>
the lauterbach has ultrafast RAM buffer and whatnot, but you don't really need such stuff for *simple* debugging
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<DocScrutinizer05>
e.g. ETM data is absolutely useless without proper software tools to read it. it's just a list of addresses in memory and timestamps and condition flags that tell you about the way a conditional intruction at that addr got executed (e.g. "less than zero" or not)
<DocScrutinizer05>
the non-conditional instructions in between don't get traced
<DocScrutinizer05>
so you need to merge that ETM buffer info with you a priori knowledge about the code on your target
<DocScrutinizer05>
the most simple tracing method is single step (either automatic or manual), in which case the CPU gets a software- or hardware-generated interupt after execution of every single intruction. Then a special monitor program on the _target_ analyzes the stack to check where the program pointer points to, and reads the instaruction at that point and writes it to a trace-logfile (basically)
<DocScrutinizer05>
then the debug monitor code does a "return from interupt" which makes CPU execute next intruction of code inder supervision, and then the next interupt happens
<DocScrutinizer05>
the software variant replaces the code by a software interupt instruction one at a time, and then on next cycle restores the original instruction at addr N and changes addr N+1 to an nterrupt instruction
<DocScrutinizer05>
with an address comparator hw breakpint you don't need that nasty sw breakpoints/interrupts - which is really nice since sometimes the restoration of code fails for some reason and you get stale software breakpoints of which the original code got lost. So you need to start all over again
<DocScrutinizer05>
and ETB/ETM is outright awesome, since you can know exactly what were the last maybe 10k of instructions the CPU did *before* it (for example) wrote 0 to that pointer you placed your breakpoint at ("data store only" hw data value comparator)
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<nicksydney>
thanks DocScrutinizer05 will buy something simple first for now and once i 'master' it than will move on to invest in something more expensive :)
<nicksydney>
and also need to invest on scope as wpwrak has suggested to me .. still collecting though :)
<DocScrutinizer05>
to start with, the cheapest JTAG adaper you can find will do
<DocScrutinizer05>
finding good software probably is harder (though I never really checked, I always had first class software and JTAG tools, like Lauterbach, so I don't know much about what's available)
<DocScrutinizer05>
basically you could use Lauterbach software with the cheapest JTAG adapter you can find, just you can't run Lauterbach software without licence key and dongle
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<DocScrutinizer05>
nicksydney: when you have a wondoze OS on a fast PC, you'll love this trace32m*.exe program. And iirc it uses trace32-view frontend which also should be able to run (maybe with another one of the free files from Lauterbach) with any arbitrary JTAG adapter, as long as you can configure it
* DocScrutinizer05
idly wonders if Lauterbach made a linux version of trace32view
<DocScrutinizer05>
oops, trace32-powerview is the name
<DocScrutinizer05>
meh, I bet that's the android code
<DocScrutinizer05>
>>On November 21, 2012, it was announced that ST-Ericsson had joined the Sailfish Alliance hence NovaThor ModAp platform would support Jolla's smartphones and Sailfish OS.[6]<< HAHAHA
<DocScrutinizer05>
AAAH yep, NovaThor L9540 been it, actually the "external Thor M7400 modem"
<DocScrutinizer05>
and the NovaThor U8500
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<nicksydney>
DocScrutinizer05: yup that's the Android cod
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<wpwrak>
plan B would be to develop debugging strategies that don't need so fancy tools. a bit of gdb (and JTAG) and thinking go a looong way
<wpwrak>
there are situations where you need more complex tools, but you may not run into these for a good while yet
<wpwrak>
also, some of those fancy tools are made to solve workflow issues that you can easily avoid. e.g., by not used closed source :)
<wpwrak>
so that's what they call lockpicks these days ;-)
<nicksydney>
these days or those days ? :)
<nicksydney>
man some fighting going on in arm-netbook mailing list
<ysionneau>
wpwrak: is the dark side the ball side ? :)
<wpwrak>
ysionneau: those rf chips have no balls
<ysionneau>
that's a shame :(
* ysionneau
goes back to his rf chip
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<nicksydney>
wpwrak: in kicad most of the labelling for component (D2, R2, etc) it is on the Cmts.User layer..any way to instruct it to put on Silkscreen ?
<wpwrak>
that's something i need to look into. i noticed that it sometimes doesn't seem to go where i want it to go. i had it working in the past, though.
<wpwrak>
(seem) perceived indirectly - my home-made pcbs don't don't have silk screen anyway
<whitequark>
something involving processing on fpgas, I guess?
<larsc>
whitequark: that looks quite good already
<whitequark>
larsc: the lens? it's pretty bad imo
<whitequark>
compared to the factory-made glass ones I've seen, of course :) I'm somewhat of a perfectionist
<ysionneau>
whitequark: I'm doing a driver for my company's rf chip
<ysionneau>
I'm learning the RF world :)
<ysionneau>
LTE rf chip
<whitequark>
ouch
<whitequark>
sounds like pain
<ysionneau>
yes there are literally tons of parameter to play with
<ysionneau>
to select power amplifier gain, bandwidth, frequency, dc offset calibration etc etc
<ysionneau>
256 32bits registers :p
<whitequark>
1) derive a single parameter, like, "RX quality" 2) use a genetic algorithm
<whitequark>
actually, that sounds just insane enough to work
<whitequark>
cc DocScrutinizer05
<ysionneau>
you got pll/mixer/filter settings
<ysionneau>
you need to be able to compute the output power taking all the rf chain into account, because the baseband tells you "I want 20 dBm output"
<ysionneau>
you need to figure out which gains to apply
<ysionneau>
fortunately I am not writting the Layer1 code, so all the scheduling is already done, I just need to control correctly the rf chip :p
<larsc>
is this a sigle chip solution?
<wpwrak>
whitequark: now, make it a bit bigger and then we'll wait for you to announce the first pictures of not only an earth-like planet of a distant star, but also of its inhabitants, waving :)
<ysionneau>
larsc: 1 baseband and 1 rf chip
<ysionneau>
no code running on the rf chip
<larsc>
and the specs?
<ysionneau>
what do you mean?
<larsc>
sampling rate, bw, etc
<ysionneau>
bandwidth can be 20 15 10 5 MHz
<ysionneau>
working on band A/C/D of LTE
<ysionneau>
TDD/FDD
<ysionneau>
it's full analog so no sampling
<ysionneau>
usually we put ADC/DAC between the baseband and the rf chip
<larsc>
ah ok
<ysionneau>
it does carrier agregation
<ysionneau>
2RX/2TX
<ysionneau>
maybe I shouldn't be giving all those informations :)
<ysionneau>
not sure what is public or not
<ysionneau>
probably nothing is public since the rf ic is just out from fab
<larsc>
yea, probably not talk about it then
<ysionneau>
my fault
<ysionneau>
larsc: does your company do lte rf chips?
<ysionneau>
ah yes
<ysionneau>
AD9357
<ysionneau>
ah you got integrated dac/adc
<ysionneau>
actually our next baseband will have integrated dac/adc I think, funny we don't put them in the same chip :)
<ysionneau>
I think we used this rf chip (ad9357) actually :o
<larsc>
ysionneau: sometimes it's a question of yield
* ysionneau
trying to translate yield
<larsc>
and sometimes it's a question of what can be connected better
<larsc>
ysionneau: how many of the chips are actually going to work
<larsc>
different components on a chip have different failure rates
<ysionneau>
yes ok
<larsc>
so if you have a lot of components on one chip and only one fails you have to throw away the whole chip
<ysionneau>
aah yes I see
<larsc>
or as they do with cpus sell the quad core as a dual core
<ysionneau>
but funny that we tend to put adc/dac on BB and your company tend to put it in rf chip
<larsc>
well we don't have a baseband, so its simple ;)
<larsc>
our latest and greatest chip is the ad9361, which can also be used for things like LTE
<larsc>
pcercuei uses it to run his own radio station though
<ysionneau>
ah nice chip!
<ysionneau>
pretty swiss knife kind of rf
<whitequark>
wpwrak: nope, wouldn't work
<whitequark>
it doesn't make sense to make a telescope that searches for exoplanets using lenses, as it's incredibly hard to make one with proper characteristics; it deforms under its own weight
<wpwrak>
maybe if you add some accelerant to the plastic
<whitequark>
not to mention making such a huge uniform slab of material is incredibly hard in the first place
<whitequark>
hence all big telescopes are reflectors
<wpwrak>
naw, make it smart, not big :)
<wpwrak>
and don't forget the accelerant. otherwise it'll take years for the light to arrive
<whitequark>
meh
<whitequark>
I believe I recently read an analysis on how to make a telescope that can resolve meter-sized features on exoplanets
<whitequark>
the trick is to completely get rid of lenses or mirrors, and use gravity wells for that
<whitequark>
i.e. you assemble a telescope as a set of spacecraft at somewhere around 20 AU, and use the Sun for refracting the light
<whitequark>
then numerically reconstruct the picture
<ysionneau>
that would be the "longer" telescope ever :)
<wpwrak>
so that's what scotty and spock are doing these days
<whitequark>
hehe
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<nicksydney>
wpwrak: read your email in the mailing list and i can contribute my time for anelok .. that's the only thing i can help you with the project :)
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<DocScrutinizer05>
(LTE chip) I wonder how that critter is supposed to *ever* pass certification, when it's missing the radio stack and the calibration